Index: third_party/WebKit/Source/core/html/ClassList.cpp |
diff --git a/third_party/WebKit/Source/core/html/ClassList.cpp b/third_party/WebKit/Source/core/html/ClassList.cpp |
index 5a749472c108ebb7740192554b389aafb9c618bf..d38aed24471a068ccf5e18d65926c93ecf0b072a 100644 |
--- a/third_party/WebKit/Source/core/html/ClassList.cpp |
+++ b/third_party/WebKit/Source/core/html/ClassList.cpp |
@@ -60,6 +60,16 @@ const SpaceSplitString& ClassList::ClassNames() const { |
return element_->ClassNames(); |
} |
+SpaceSplitString& ClassList::MutableSet() { |
+ // We can't mutate element_->ClassNames() because it is used to compare class |
+ // names before/after class attribute change. |
+ if (element_->HasClass()) |
+ mutable_set_ = ClassNames(); |
+ else |
+ mutable_set_ = SpaceSplitString(); |
+ return mutable_set_; |
+} |
+ |
DEFINE_TRACE(ClassList) { |
visitor->Trace(element_); |
DOMTokenList::Trace(visitor); |